This invention relates to devices for assisting in retrieving submerged objects such as fishing rods, guns, other sporting equipment, and items of value generally, which have accidentally been dropped into a body of water.
Numerous retrieval devices have been developed in the past. A few of the patents which describe such devices are as follows: Berndt, U.S. Pat. No. 2,198,755; Cardinal, U.S. Pat. No. 2,479,098; Norris et al, U.S. Pat. No. 2,539,548; Kanaley, U.S. Pat. No. 2,785,420; Hinman, U.S. Pat. No. 3,105,980; Foss et al, U.S. Pat. No. 3,334,364; and May et al, U.S. Pat. No. 3,407,418.
The devices described in the above patents may be divided into three general classifications. In the Foss patent, a soluble material simply holds the float in place until the soluble material dissolves. The second group encompasses the Berndt, Cardinal, and Norris et al patents, in which a soluble material holds the float and a spring in place until the soluble material dissolves in water. In a third group may be placed the patents to Kanaley, Hinman, and May et al, in which the device includes a reactant material which has a strongly exothermic reaction with water, such as sodium metal, calcium carbide, or the alkali metal oxides. In the Kanaley and May et al patents, the gas generated by the reaction forces the float away from the body of the device. In the Hinman patent the reactant material covers a string holding a spring in place and the reaction burns through the string to release the float.
It is readily apparent that the inclusion of an exothermic reactant provides an extremely dangerous device. In these types of devices, especially those described above, the reactant may be subject to atmospheric moisture, and the person handling the device is subject to severe injury.
Most of the prior art devices are unsatisfactory and impractical because they are either too complicated to manufacture at a reasonable price, are not designed for efficient usage, or are intended to be used one time only.